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Handle unreachable code in the dominates functions. This changes users when

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needed for correctness, but still doesn't clean up code that now unnecessary
checks for reachability.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153755 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2012-03-30 16:46:21 +00:00
parent 0e4fa5ff36
commit 092c5ccf5b
6 changed files with 239 additions and 11 deletions
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31
include/llvm/Analysis/Dominators.h
View File

@ -359,8 +359,19 @@ public:
bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) const {
// A node trivially dominates itself.
if (B == A)
return true;
// An unreachable node is dominated by anything.
if (!isReachableFromEntry(B))
return true;
// And dominates nothing.
if (!isReachableFromEntry(A))
return false;
const DomTreeNodeBase<NodeT> *IDom;
if (A == 0 || B == 0) return false;
while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
B = IDom; // Walk up the tree
return IDom != 0;
@ -369,10 +380,14 @@ public:
/// isReachableFromEntry - Return true if A is dominated by the entry
/// block of the function containing it.
bool isReachableFromEntry(const NodeT* A) {
bool isReachableFromEntry(const NodeT* A) const {
assert(!this->isPostDominator() &&
"This is not implemented for post dominators");
return dominates(&A->getParent()->front(), A);
return isReachableFromEntry(getNode(const_cast<NodeT *>(A)));
}
inline bool isReachableFromEntry(const DomTreeNodeBase<NodeT> *A) const {
return A;
}
/// dominates - Returns true iff A dominates B. Note that this is not a
@ -380,10 +395,16 @@ public:
///
inline bool dominates(const DomTreeNodeBase<NodeT> *A,
const DomTreeNodeBase<NodeT> *B) {
// A node trivially dominates itself.
if (B == A)
return true; // A node trivially dominates itself.
return true;
if (A == 0 || B == 0)
// An unreachable node is dominated by anything.
if (!isReachableFromEntry(B))
return true;
// And dominates nothing.
if (!isReachableFromEntry(A))
return false;
// Compare the result of the tree walk and the dfs numbers, if expensive

3
include/llvm/Analysis/LoopInfo.h
View File

@ -762,7 +762,8 @@ public:
InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB);
I != E; ++I) {
typename InvBlockTraits::NodeType *N = *I;
if (DT.dominates(BB, N)) // If BB dominates its predecessor...
// If BB dominates its predecessor...
if (DT.dominates(BB, N) && DT.isReachableFromEntry(N))
TodoStack.push_back(N);
}

18
lib/VMCore/Dominators.cpp
View File

@ -88,8 +88,13 @@ bool DominatorTree::dominates(const Instruction *Def,
const BasicBlock *UseBB = User->getParent();
const BasicBlock *DefBB = Def->getParent();
assert(isReachableFromEntry(DefBB) && isReachableFromEntry(UseBB) &&
"We only handle reachable blocks");
// Any unreachable use is dominated, even if Def == User.
if (!isReachableFromEntry(UseBB))
return true;
// Unreachable definitions don't dominate anything.
if (!isReachableFromEntry(DefBB))
return false;
// An instruction doesn't dominate a use in itself.
if (Def == User)
@ -119,8 +124,13 @@ bool DominatorTree::dominates(const Instruction *Def,
const BasicBlock *UseBB) const {
const BasicBlock *DefBB = Def->getParent();
assert(isReachableFromEntry(DefBB) && isReachableFromEntry(UseBB) &&
"We only handle reachable blocks");
// Any unreachable use is dominated, even if DefBB == UseBB.
if (!isReachableFromEntry(UseBB))
return true;
// Unreachable definitions don't dominate anything.
if (!isReachableFromEntry(DefBB))
return false;
if (DefBB == UseBB)
return false;

1
unittests/CMakeLists.txt
View File

@ -139,6 +139,7 @@ set(VMCoreSources
VMCore/PassManagerTest.cpp
VMCore/ValueMapTest.cpp
VMCore/VerifierTest.cpp
VMCore/DominatorTreeTest.cpp
)
# MSVC9 and 8 cannot compile ValueMapTest.cpp due to their bug.

195
unittests/VMCore/DominatorTreeTest.cpp Normal file
View File

@ -0,0 +1,195 @@
#include "llvm/Instructions.h"
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Assembly/Parser.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
using namespace llvm;
namespace llvm {
void initializeDPassPass(PassRegistry&);
namespace {
struct DPass : public FunctionPass {
static char ID;
virtual bool runOnFunction(Function &F) {
DominatorTree *DT = &getAnalysis<DominatorTree>();
Function::iterator FI = F.begin();
BasicBlock *BB0 = FI++;
BasicBlock::iterator BBI = BB0->begin();
Instruction *Y1 = BBI++;
Instruction *Y2 = BBI++;
Instruction *Y3 = BBI++;
BasicBlock *BB1 = FI++;
BBI = BB1->begin();
Instruction *Y4 = BBI++;
BasicBlock *BB2 = FI++;
BBI = BB2->begin();
Instruction *Y5 = BBI++;
BasicBlock *BB3 = FI++;
BBI = BB3->begin();
Instruction *Y6 = BBI++;
Instruction *Y7 = BBI++;
BasicBlock *BB4 = FI++;
BBI = BB4->begin();
Instruction *Y8 = BBI++;
Instruction *Y9 = BBI++;
// Reachability
EXPECT_TRUE(DT->isReachableFromEntry(BB0));
EXPECT_TRUE(DT->isReachableFromEntry(BB1));
EXPECT_TRUE(DT->isReachableFromEntry(BB2));
EXPECT_FALSE(DT->isReachableFromEntry(BB3));
EXPECT_TRUE(DT->isReachableFromEntry(BB4));
// BB dominance
EXPECT_TRUE(DT->dominates(BB0, BB0));
EXPECT_TRUE(DT->dominates(BB0, BB1));
EXPECT_TRUE(DT->dominates(BB0, BB2));
EXPECT_TRUE(DT->dominates(BB0, BB3));
EXPECT_TRUE(DT->dominates(BB0, BB4));
EXPECT_FALSE(DT->dominates(BB1, BB0));
EXPECT_TRUE(DT->dominates(BB1, BB1));
EXPECT_FALSE(DT->dominates(BB1, BB2));
EXPECT_TRUE(DT->dominates(BB1, BB3));
EXPECT_FALSE(DT->dominates(BB1, BB4));
EXPECT_FALSE(DT->dominates(BB2, BB0));
EXPECT_FALSE(DT->dominates(BB2, BB1));
EXPECT_TRUE(DT->dominates(BB2, BB2));
EXPECT_TRUE(DT->dominates(BB2, BB3));
EXPECT_FALSE(DT->dominates(BB2, BB4));
EXPECT_FALSE(DT->dominates(BB3, BB0));
EXPECT_FALSE(DT->dominates(BB3, BB1));
EXPECT_FALSE(DT->dominates(BB3, BB2));
EXPECT_TRUE(DT->dominates(BB3, BB3));
EXPECT_FALSE(DT->dominates(BB3, BB4));
// BB proper dominance
EXPECT_FALSE(DT->properlyDominates(BB0, BB0));
EXPECT_TRUE(DT->properlyDominates(BB0, BB1));
EXPECT_TRUE(DT->properlyDominates(BB0, BB2));
EXPECT_TRUE(DT->properlyDominates(BB0, BB3));
EXPECT_FALSE(DT->properlyDominates(BB1, BB0));
EXPECT_FALSE(DT->properlyDominates(BB1, BB1));
EXPECT_FALSE(DT->properlyDominates(BB1, BB2));
EXPECT_TRUE(DT->properlyDominates(BB1, BB3));
EXPECT_FALSE(DT->properlyDominates(BB2, BB0));
EXPECT_FALSE(DT->properlyDominates(BB2, BB1));
EXPECT_FALSE(DT->properlyDominates(BB2, BB2));
EXPECT_TRUE(DT->properlyDominates(BB2, BB3));
EXPECT_FALSE(DT->properlyDominates(BB3, BB0));
EXPECT_FALSE(DT->properlyDominates(BB3, BB1));
EXPECT_FALSE(DT->properlyDominates(BB3, BB2));
EXPECT_FALSE(DT->properlyDominates(BB3, BB3));
// Instruction dominance in the same reachable BB
EXPECT_FALSE(DT->dominates(Y1, Y1));
EXPECT_TRUE(DT->dominates(Y1, Y2));
EXPECT_FALSE(DT->dominates(Y2, Y1));
EXPECT_FALSE(DT->dominates(Y2, Y2));
// Instruction dominance in the same unreachable BB
EXPECT_TRUE(DT->dominates(Y6, Y6));
EXPECT_TRUE(DT->dominates(Y6, Y7));
EXPECT_TRUE(DT->dominates(Y7, Y6));
EXPECT_TRUE(DT->dominates(Y7, Y7));
// Invoke
EXPECT_TRUE(DT->dominates(Y3, Y4));
EXPECT_FALSE(DT->dominates(Y3, Y5));
// Phi
EXPECT_TRUE(DT->dominates(Y2, Y9));
EXPECT_FALSE(DT->dominates(Y3, Y9));
EXPECT_FALSE(DT->dominates(Y8, Y9));
// Anything dominates unreachable
EXPECT_TRUE(DT->dominates(Y1, Y6));
EXPECT_TRUE(DT->dominates(Y3, Y6));
// Unreachable doesn't dominate reachable
EXPECT_FALSE(DT->dominates(Y6, Y1));
// Instruction, BB dominance
EXPECT_FALSE(DT->dominates(Y1, BB0));
EXPECT_TRUE(DT->dominates(Y1, BB1));
EXPECT_TRUE(DT->dominates(Y1, BB2));
EXPECT_TRUE(DT->dominates(Y1, BB3));
EXPECT_TRUE(DT->dominates(Y1, BB4));
EXPECT_FALSE(DT->dominates(Y3, BB0));
EXPECT_TRUE(DT->dominates(Y3, BB1));
EXPECT_FALSE(DT->dominates(Y3, BB2));
EXPECT_TRUE(DT->dominates(Y3, BB3));
EXPECT_FALSE(DT->dominates(Y3, BB4));
EXPECT_TRUE(DT->dominates(Y6, BB3));
return false;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
}
DPass() : FunctionPass(ID) {
initializeDPassPass(*PassRegistry::getPassRegistry());
}
};
char DPass::ID = 0;
Module* makeLLVMModule(DPass *P) {
const char *ModuleStrig =
"declare i32 @g()\n" \
"define void @f(i32 %x) {\n" \
"bb0:\n" \
" %y1 = add i32 %x, 1\n" \
" %y2 = add i32 %x, 1\n" \
" %y3 = invoke i32 @g() to label %bb1 unwind label %bb2\n" \
"bb1:\n" \
" %y4 = add i32 %x, 1\n" \
" br label %bb4\n" \
"bb2:\n" \
" %y5 = landingpad i32 personality i32 ()* @g\n" \
" cleanup\n" \
" br label %bb4\n" \
"bb3:\n" \
" %y6 = add i32 %x, 1\n" \
" %y7 = add i32 %x, 1\n" \
" ret void\n" \
"bb4:\n" \
" %y8 = phi i32 [0, %bb2], [%y4, %bb1]\n"
" %y9 = phi i32 [0, %bb2], [%y4, %bb1]\n"
" ret void\n" \
"}\n";
LLVMContext &C = getGlobalContext();
SMDiagnostic Err;
return ParseAssemblyString(ModuleStrig, NULL, Err, C);
}
TEST(DominatorTree, Unreachable) {
DPass *P = new DPass();
Module *M = makeLLVMModule(P);
PassManager Passes;
Passes.add(P);
Passes.run(*M);
}
}
}
INITIALIZE_PASS_BEGIN(DPass, "dpass", "dpass", false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
INITIALIZE_PASS_END(DPass, "dpass", "dpass", false, false)

2
unittests/VMCore/Makefile
View File

@ -9,7 +9,7 @@
LEVEL = ../..
TESTNAME = VMCore
LINK_COMPONENTS := core support target ipa
LINK_COMPONENTS := core support target ipa asmparser
include $(LEVEL)/Makefile.config
include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest